@Article{dempster77,
author = {A. P. Dempster and N. M. Laird and D. B. Rubin},
title = {Maximum likelihood from incomplete data via the {E}{M} algorithm},
journal = {Royal Statistical Society Series B},
year = {1977}
}

@book(cowell99,
        author = {Robert G. Cowell and A. Philip Dawid and  Steffen L. Lauritzen and David J. Spiegelhalter},
        title = {Probabilistic Networks and Expert Systems},
        publisher = {Springer-Verlag},
        address = {New York},
        year = 1999
)